Delta Air Lines Inc. and Northwest Airlines Corp. pilot union leaders are developing a plan for meshing their executive councils, as their companies prepare to merge by year's end to form the world's biggest carrier.

The two master executive councils met in Chicago on Sunday to discuss governance, financial data, industry outlook and a plan for combining their leadership, the Northwest pilots said in an e-mailed memo. The Delta and Northwest employees belong to different chapters of the Air Line Pilots Association.

The pilots haven't yet resolved a dispute over how to combine their seniority lists, a disagreement that almost scuttled the companies' merger discussions in February and March. The pilots have agreed to a new joint contract with Delta management, and a three-person arbitration panel is crafting a single seniority list and will issue a decision by Nov. 20.